Oil burner and system



May 2, 1944.

c. L. RAYFIELD 2,347,842

OIL BURNER AND SYSTEM Filed Sept. 27, 1939 4 She etsS1 1eet l CHARZES'L. RA man y 1944- c. L. RAYFIELD OIL BURNER AND SYSTEM Filed se t. 27,1939 s A m s VE 0F I CHARLES L. RAYF/ELO y 1944- c. L. RAYFIELD2,347,842

OIL BURNER AND SYSTEM Filed Sept. 27, 1939 4 Sheets-Sheet 4 CHARLES L.RA YF/ELD Patented May 2, 1944 UNITED STATES PATENT OFFICE 2,347,842011. BURNER AND SYSTEM Charles L. Hayfield, Chicago, Ill., assignor, bymesne assignments, to C. L. Rayfield Company, Chicago, 111., acorporation of Illinois Application September 27, 1939, Serial No.296,718

Claims.

The present invention relates in general to improved means for theburning of oil for heating purposes and amongst other things isprimarily concerned with improvements in such apparatus to the end thatthe less expensive, more viscous oils containing a greater number ofheat units may be efficiently utilized for heating purposes.

Heretofore, oil burners for domestic heating, such as utilized for theheating of homes, apartment buildings, and the like, have been limitedalmost entirely to the use of the more highly refined and lighter oilswhich not only contain a less number of heat units, but are moreexpensive than the heavier and more viscous oils.

This limitation has resulted to a large extent from the apparentinability of manufacturers to heretofore build suitable apparatus foreflicient- 1y burning the heavier grades of oil, which could beassembled into a compact unit suitable for domestic installations. Whereattempts were made to use the heavier oils, the installed apparatususually entailed a complicated arrangement of piping between widelyspaced parts of the apparatus and required considerable space forinstallation, all of which was objectionable and unsightly, especiallyin cases where the spaces containing the burner apparatus were to beutilized for game and play rooms, and the like.

More specifically, most oil burners are arranged to burn the so-called"Light oil No. 3, and it has heretofore been difiicult to providesatisfac tory apparatus for domestic heating which could be efficientlyutilized to burn oils as heavy as the so-called No. 5 or "No. 6.

Having the foregoing in mind, the present invention contemplates as aprimary object the provision of an improved oil burner and system whichwill efliciently and economically burn the heavier, more viscous oils.

A further object of the invention is to provide an improved oil burnerand system embodying improved means for pre-heating the oil.

A further object of the invention is to provide an improved oil burnerand system wherein air may be mixed with the oil under pressure to forma compressible mixture, before the mixture is atomized in the burnernozzle the apparatus being so arranged that th amount of air may beautomatically controlled.

A still further object is to provide improved means in an oil burner andsystem ior'carbureting the oil by the induction of air thereinto beforeit reaches the burner nozzle It is likewise a further object of theherein described invention to provide an improved oil burner and systemhaving novel pumping mechanism in which the oil may be pre-heated andmixed with air. I

A further object of the invention is to provide improved means in an oilburner and system for purging and flushing the oil nozzle, when theburner is shut down.

Another object of the invention is to provide an improved reliefarrangement in the oil path of the burner, whereby oil may .be returnedto a source of supply, whenever the burner nozzle becomes clogged.

A still further object of the herein described invention is to providean improved oil burner in which metered quantities of oil are burned,and anysurplus pumped oil is automatically by passed back to a supplysource.

Yet another object is to provide an improved oil burner and system forthe burning of relatively heavy, viscous grades of oil, wherein theapparatus is equipped with improved control means for delaying startingof the burner until the oil has been pro-heated to a preterminedtemperature.

Other objects and features of the invention will more fully appear fromthe following detailed description taken in connection with theaccompanying drawings, which illustrate a single embodiment thereof, andin which:

Figure 1 is a plan view of oil burner apparatus embodying the featuresof the present invention;

Figure 2 is a longitudinal sectional view taken through the pumping partof the apparatus to show the details of the construction thereof, takensubstantially on line 11-11 of Figure 1;

Figure 3 is a detailed view, partly in section, showing the valvingarrangement of the pumping parts, taken substantially on line IIIIH ofFigure 2-;

Figure 4 is a view looking into the housing for certain of the controlequipment mounted on the burner, the cover of the housing being removedto show the control elements therein;

Figure 5 is an enlarged fragmentary sectional view showing the detailsof construction of the bleeder valve as utilized in the presentinvention, taken substantially on line VV of Figure 1;

Figure 6 is an enlarged fragmentary sectional 'view' of the carburetorconstruction utilized in the present invention, taken substantially online VI-VI of Figure 1; and

Figure 7 is a schematic view of the oil burner anddiagrammaticallydisclosing the piping systerns for oil and air, and alsodiagrammatically showing the control equipment and the electricalconnections thereof.

As shown on the drawings:

From a consideration of the apparatus illustrated in Figure 1 of thedrawings, it will be apparent that the oil burner and system of thepresent invention provides a compact unit assembly which may be readilyapplied to already installed or existing furnaces and boilers forheating purposes.

Burner apparatus in general As shown in Figure 1, the burner unitcomprises in general an air blower A, ;fue l pumping mechanism B, and amain driving motor for actuating the blower and pumping mechanism.

The blower A is of conventional construction and comprises a mainhousing portion III for enclosing the blower blades orimpeller (notshown) which is connected to the driving shaft of the motor. Thishousing terminates at one end in a tubular extension II which forms anair inlet to the center of the housing Ill, the extension beingcircumferentially provided with a plurality of spaced air inlet openings12. Control of the inlet openings .I2 isaccomplished by ,means of aslide plate I3 which is suitably supported on the outersurface of theextension .l,| forsliding movement thereover. This plate ,is providedwith spaced openings I4 which are adapted to cooperate with the-openingsI2 and adjust the effective air inlet openings so as to vary the amountof inlet air taken in by the blower.

The housing In is provided with a tubular extension |5 on its forwardside, this extension defining an air nozzle for supplying the ,maincombustion air to a fuel atomizing nozzle I6 mounted therein, as shownin Figure .7.

Returning again :to Figure .1, the pumpin mechanism :B'comprisesarotarytype of pump I] for the pumping of oil only, and a secondpuinp l8of the reciprocable type for the pumping of air and -oil for a purposewhich will hereafter be more fully explained.

The rotary pump I1 is provided with a .suit- .able pipe connectionfitting I9 at its inlet, and a suitable pipe connection fitting atitsoutlet.

The reciprocating pump i8, as more specifically shown in Figure 2,comprises ;a housing or casing 2| which serves at one side as a suppo tfor the rotary pump housing structure 22 which encloses the rotarypumprotor23, this rotor bein mounted at one .end of a shaft .24 whichalso serves as the shaft for the pumpi elements of the reciprocatingpump. Ifhe shaft 2, and the opposite wall of the housing .2I ,iromjthatto which the rotary pump housing is secured is provided with a suitableshaft bearing ;25 that is secured to the pump housingby means of,suitable bolts '26.

The top wall of the housing=2| is providedwith an opening 21 forreceivingthe vlowermost'end of acylinder defining block28 having-aperipheral flanged portion 29 for-receiving'holding down screws or bolts3Bby means of which the block is secured to thethousing 2|.

The block 28 defines a pair of aligned cylinders 3| and 32forreciprocably and operatively receiving the pistons '33 and 3.4. :Eachof thepistons is connected by means of aconnecting link 35 to aneccentric on the shaft lL-the. eccentrics for'actuating the two pistonsbeing' in 180.relaf tion. That is, when, one piston. is at. the" bottomof its stroke, the other piston will be at the top of its stroke.

It will be noted that the cylinder bores extend entirely through thecylinder block and are covered by a cap member 36 which defines theoutlet manifold from the cylinder, a suitable gasket 31 preferably beingprovided at the joint between the cap and the uppermost end of theassociated cylinder block.

As shown in Figure 3, a common inlet manifold 38 is suitably secured atone side of the cap member, this manifold having separate inletconnections 39 and 40 respectively communicating through ducts 4|withthe interior of the cylinders, the ducts terminating in the undersurfaceof the cap 36 in each cylinder. The ducts 4| in eachcylinder arerespectively controlled by a downwardly opening member or flap valve 42which is anchored at one end as at 43 to the undersurface of the cap 38with its free end overlying the entranceopenings of the ducts 4| intothe cylinder.

As shown in Figure 2, the cap 35 has a longitudinally extending bore 44having one end connected with a pipe connection fitting 45 and its otherend connected with a pipe connection fitting 46. Intermediate the endsof the bore .44, the cap is provided with portions defining a valvesocket 41 axially alignedand above each of the cylinders. This socket.is closed at its bottom, except for one or more outlet ports 48.

The upper end of each socket is arranged to be closed by a suitable plug49 which may be screwed into the upperend of a socket against .a

suitabl gasket 50. This plug is recessed atits innermost end to receiveone end of an expansion spring 5| which acts to bias a valve disk 52into seated position over the outlet port from the associated cylinder.

In addition to the valving arrangement of ports as described above, theoutlet valve for cylinder 32 is additionally provided with a small=by-pass port 53 which enables a small amount of :the fluid being pumpedin cylinder 32 to be Joy-passed around its associated outlet valve diskThe bottom wall of the housing 2| of the reciprocating pump structure isprovided with a constructed .of a metal which preferably has a .highheat conducting characteristic, such as aluminum. The member 54 isconstructed with a relatively thin shelled integrally formed cappedportion 51 which extends upwardly through the opening 55 into thehousing 2| and provides a downwardly opening recess 58 adapted toaxially receive therein an electric heating unit 59. This heating-unitcomprises a body portion of insulating material, such as an asbestoscomposition,

which is provided with a helically extending groove 60 in which asuitable heating element or resistance wire BI is disposed. The ends ofthe heating element are connected to suitable terminal studs-62 and 63which are mounted in the body of the heating element and have threadedends projecting from the recess or socket 58, these threaded ends beingprovided with suitable nuts '64 formaking connection to energy supplyingconductors.

The. heating element is retained within the socket 58 by means of aretaining bolt 65 extending through the bot om .of the c pped Portionand a suitable bore in the body portion of the heater body, a nut 6511being threaded onto the bolt 65 to cooperate with the head of the bolt'for clamping the body portion of the heater against the bottom of thecupped portion.

With the construction just described, the heater may be easily removedfrom its position in the socket 58 simply by removing the nut 6511,Whereupon the heater may be taken out as a unit. Such an arrangement isparticularly advantageous as it enables ready replacement of a heatershould it become burned out, or in the event that it is desired toinstall heaters for operation on diiTerent voltages which may beavailable in different installations of the oil burner equipment.

As shown in Figure 1, the interior of the housing 2| is maintained opento atmosphere through a suitable breather 66.

The housing 2! of the reciprocating pumping mechanism comprises areservoir for receiving oil which is supplied from the outlet connectionof the rotary pump through a pipe connection 61, as shown in Figure 1,this pipe being provided with a number of turns which encircle theextension of the bore, these turns being in heat receiving relation withthe burner nozzle and the fuel which is being atomized and burned. Afterencircling the extension I5, the pipe 61 is carried to the inlet of afloat valve 68 having an outlet which is connected by a suitable pipeconnection 69 to the interior of the housing 2 i The float valve 68operates to maintain a predetermined supply of oil within the housing2!. Normally this oil level is approximately at the shaft 24 so that theoperation of the driving eccentrics for the links will act to churn andagitate the oil and enable its being more readily heated by the electricheater in the bottom of the pump housing 2| and by the heat generated byfriction during operation of the pump parts.

By conducting the oil through pipe 61 through the turns around extensionIS, the heating of the on is augmented. In fact, after the burner hasstarted to operate, the electric heater is de-energized and the oil issufficiently heated by its being passed around the extension [5.

The float valve 68 is also vented to atmosphere through a suitablebreather 10.

On the opposite side of the blower casing I D from the extension l5,there is supported a housing 1! for the local control mechanism, thehousing H having a removable cover 12.

Referring to Figure 4, the local control mechanism will now bedescribed. Within the housing, there is provided a supporting bracket 13which is secured to the rear wall of the housing by means of suitablescrews 14. This bracket has a forwardly projecting L-shaped flangeportion defining a long leg 15 and an uppermost shorter leg 16.

Associated with the uppermost leg 16 of the bracket is an elongate arm11 which is flexibly connected to the leg 16 of the bracket by means ofa leaf spring as shown at 18. This spring permits vertical swingingmovement of the arm 11, this swinging movement being adjustable betweenabutment nuts 19 and 80 threaded on a stud bolt 8|, these nuts beingadjustably positionable on either side of the arm 1'! to limit itsswinging movement.

The arm 1'! is normally biased in a downward direction by a tensicnedspring 82 having one end anchored to the leg 15 of the bracket, and itsother end anchored to the arm 11.

The arm ll is moved upwardly in response to the action of the thermalresponsive closed system. This system comprises a bellows 83 which isrigidly secured at one end to the leg 15 of the bracket and has itsuppermost end provided with a head member 84 which bears against theunderside of the arm 11 adjacent its connection to the leg 16 of'thebracket. Connecting the interior of the bellows 83 with a bulb 85 is ahollow conductor 86. The bulb, bellows, and conductor are filled with athermal responsive medium, so that as the temperature to which the bulb85 is subjected is varied, the bellows 83 will be caused to expand orcontract depending upon whether the temperature is increased ordecreased. Expansion of the bellows moves the arm Tl upwardly againstthe tension of spring 82, whereas contraction of the bellows permits thespring 82 to move the arm H in the opposite direction.

' The bulb 85 in the present instance is mounted within the pumpinghousing 2| previously described, and as shown in Figure 1. Thus, thebellows 83 and consequently the arm 11 will be moved up and down inresponse to variations in temperature of the oil within the housing 2!.

The movements of the arm T! are utilized for the opening and closing ofswitches. For this purpose a switch supporting bracket 81 is pivoted asat 88 for swinging movement, and this bracket is pivotally connected toone end of a link 89, the other end of this link being pivotallyconnected to the free end of arm 11.

One end of the bracket 81 carries a two-electrode type mercury switch 90which is adapted in the down position of arm 71 to interconnect a pairof circuit conductors 9| and 92. The other end of the bracket 81 carriesa three-electrode mercury type of switch 93 which is arranged in theclosed position of switch 90 to interconnect conductors 94 and 96.However, when the arm 1! is raised, the bracket 81 will be rotatedcounter-clockwise and carry the switches to such position that theswitch 90 will open its contact and switch 93 will disconnect theconductors 94 and 96 and connect conductor 94 with a conductor 91. Theconductors connected with the switch may be brought out to suitableterminal blocks Within the housing I I.

There is also associated with the control mechanism, just described, anadjustable air intake valve 98 which is also supported upon the leg 15of bracket 13. This valve is provided with a stem 99 having a threadedextension I00 at its uppermost end for receiving suitable nuts Ifll, thethreaded extension extending through a suitable opening in the arm 17.By adjusting the nut H31, the amount of opening of the air valve may bedetermined in relation to the movement of arm 11. Moreover, regulationof the valve opening is adjustable by means of an adjusting screw 492.The air valve is connected to and controls the inlet of an air pipe I03.

Oil system Referring now'to Figure "I, the oil system will now bedescribed. The oil is taken from a suitable source of supply such as atank Hi4, which interior of the casing 2| of the reciprocating pumpmechanism. -In other words, the float valve maintains a substantiallyconstant oil level Within the casing 21 at all times.

'From the casing U the oil is drawn through a metering valve I66 ofconventional construction by the action of the piston associated withcylinder 32 of the reciprocating pumping mechanism.

After the oil passes through the metering valve, it is carried through apipe I01 to the intake of cylinder 32, and in so doing is conductedthrough a carburetor device I08.

This carburetor is constructed as specifically shown in Figure 6, andcomprises an elongate body .portion I09 having a longitudinallyextending bore H enlarged at its ends for receiving pipe connections. Atits lowermost end, the bore I'Ill istapped by the connection of pipe I03which extends laterally from the body. The body I09 is so positioned inrelation to the float valve 68 that the oil level in the float valvewill also maintain an oil level in the body I09 which is above theentrance of the air pipe I03. It will therefore be evident that as theoil flows through the body I09 from the bottom towards the top thereof,as shown in Figure 6, air will bedrawn into the oil stream. The air andoil will thus become mixed and an attenuated mixture of air and oilformed. It will thus be apparent that the piston acting in cylinder 32will pump an attenuated mixture of air and oil and discharge it into theoutlet manifold of the reciprocating pump mechanism.

The rotary pump I1 is arranged to pump a greater amount of oil than willbe required to be delivered through the metering valve. The surplus oil,particularly when the float valve is closed, will be delivered through.a return pipe III back to the supply source in tank I04. The pipe IIIcontains a relief valve H2, which is set to open at approximately one totwo pounds oil pressure acting in the direction of flow of oil in itsreturn to the supply tank.

The attenuated mixture of air and oil, the oil having been carbureted inthe carburetor I08 and further mixed under pressure in the cylinder 32and discharged into the outlet manifold of the reciprocating pumpmechanism, will build .up a pressure in a pipe line II3 which connectsthe outlet manifold through a ball relief valve IM with the pipe IIIjust ahead of relief valve H2. The relief valve H4 is of the ball typeand is set to open at substantially 90 pounds pressure.

Connected 'ahead of the relief valve H4 is a pipe I I5 which connectsthrough a bleeder valve I I B toa closed tank or container I H.

The construction of this bleeder valve is disclosed in detail in Figure5. As will be noted, the bleeder valve comprises an elongate casing IIBhaving a longitudinally extending bore I I9 which communicates at itsinnermost end with an expanded bore portion I20 to form a valve seat.The valve mechanism is housed within the portion I20 and comprises avalve member I2! having a rounded nose portion adapted to seat upon theinnermost end of the bore N9, the valve member being resilientlyactuated to seated position by means of an expansion spring I22.

The rounded seating end of the valve member is provided with a smallsurface'groove I 23 which permits bleeding of air from the pipe II3 intothe tank In. During normal operation of the .bu1ner,,the bleedingofairinto the tankl I'l will build up an air pressure in the tank ofsubstantially the same as the operating pressure at the nozzle. Thistank in the line obviates surges and-the air therein is used for purgingand cleaning as described hereinafter. During normal operation, thevalve member I2I will remain in closed position as shown in Figure 5.

Air system As previously described, air is taken in through the pipe I03by the carburetor I08 and mixed with the pumped oil to form anattenuated mixture of air and oil. The piston of the reciprocating pumpmechanism which is associated with cylinder BI is utilized for thepumping of air only, the inlet to this cylinder being supplied throughan air pipe I24 which is carried to and has its inlet end disposedwithin the control housing II, this housing protecting the air inletagainst the entrance of dirt and other objectionable materials.Operation of the piston in cylinder 3| compresses the air and dischargesit into the manifold of the reciprocating pumping mechanism where itcombines and is further mixed with the attenuated mixture dischargedfrom pumping cylinder 32. The manifold from the reciprocating pumpingmechanism is connected to a pipe I25 which conducts the air and oil asthey are mixed to the atomizing nozzle I6, where the mixture isdischarged at pressures ranging from substantially 40 to pounds. Theatomized fuel, when ignited, is burned in the combustion supporting airdelivered from the blower through the tubular extension I5.

A governing effect is provided by mid-point positioning of the valve 98which is determined by the temperature of the compressor as reflected onthe bulb 85. Thus Where there is a high boiler room temperature thecompressor chamber temperature will be higher, causing the bellows 83 toexpand and push its head member 84 against the bar I8, thus opening thevalve to admit additional air and maintain the desired even flame.

Control mechanism control devices are utilized in order that the burnermay be automatically started and stopped according to the heatingrequirements.

As further shown in Figure 7, the control mechanism in the casin H maybe coordinated with additional control relays, etc., which may bevariously constructed to accomplish the desired control of the burner.In the present instance, I have shown schematically a repulsion typerelay as generally indicated at I 20. This relay comprises a magneticyoke I21 with which there is associated a fixedly mounted primary coilI28 and a movably mounted secondary coil I29 which is supported on apivotally mounted arm I30. With this type of relay, when the primarycoil I28 is energized, the secondary coil is energized due to thetransformer effect between the coils. At the same time, magneticrepulsion between the primary and secondary coils causes the secondarycoil to swing away from the primary coil. This action brings the arm 30to a constitute a two-electrode mercury switch I33 carried on aswingable bracket and normally biased to open position. The bracket isarranged to be latched by a suitable latch member I34 of bi-metallicmaterial. The safety switch is moved to normally closed position inwhich it is latched by the bi-metallic member I34, but upon thetemperature of the bi-metallic metal of the latch reaching apredetermined amount, the latch member will release the safety switchand permit it to be biased to open position. The temperature of thebi-metallic latch member is controlled by means of a heating coil I35.

As also included in the control diagrammatically represented herein, aflue thermostat relay I36 which is responsive to flue temperatures, whencold, is arranged to interconnect a pair of contacts I31, but, whenheated, to open the contacts I31 and close another pair of contacts I33.

As in most control systems for oil burners, the present system includesa room thermostat as generally indicated at I39 having a pair ofnormally opened contacts I49, which are adapted to close upon a rise ofroom temperature.

Operation Let it be assumed that the oil burner has been standing idleand that the oil in the casing 2| i cold. The control devices will thenbe in their normal positions as shown in Figure 7.

Under such conditions, it will be noted that th primary coil of therepulsion relay will be connected to a source of current supply I4Ithrough the following circuit: from one side of the current supplythrough the closed contacts of safety switch I32, conductor I42 to oneside of primary coil I28, conductor I43, and thence through conductorI44 to the other side of the main current supply. Thus the primary coilis across the line and will be energized. However, the primary coil willnot repulse the secondary coil I29, since it is open-circuited as theresult of the contacts I 46 of the room thermostat in the secondary coilcircuit being in open position.

Let it now be assumed that the thermostat calls for heat, and that thisthermostat closes its contacts I40 due to fall of room temperature.Closing of the thermostat contacts I46 operates to close the secondarycoil circuit as follows: from one terminal of coil I29 through conductorI45, conductor I46, conductor 92, the contacts of switch 90, conductor9|, conductor I41, conductor I48, contacts I49, conductor I49, andthence back to the other terminal of coil I29. The secondary coilcircuit thus being completed, current will flow in the secondary coilwith the result that the secondary coil will be repulsed from theprimary coil, and the relay will operate to close contacts I3I.

Closing of contacts I3I energizes the heater 59 in the bottom of casing2| through the following circuit: from one side of the current supply IM, through the contacts of the safety switch I 32, conductor I42,contacts I3I, conductor I59 to one side of the heating element of theheater 59, and the other side of this heating element through conductor96, the closed'contact switch 93, and thence through conductor 94 to theother side of the current supply.

The heater 59 continues to pre-heat the oil in the casing 2|. Thisheating of the oil continues until it reaches substantially atemperature of 165 F. As the temperature of the oil continues toincrease, the closed thermal responsive system expands the bellows 83and causes switches 99 and 93 to move to a position wherein they tiltdownwardly to the right instead of downwardly to the left. In thischanged position, the contactsof switch are opened, and conductor 94 isdisconnected relative to conductor 96, whereupon the circuit through theheater 59 is opened. At the same time, conductor 94 is connected withconductor 91 and the motor C of the oil burner becomes energized throughth following circuit: from one side of. the electric supply circuit,through the contacts of safety switch I32, conductor I42, contacts I3I,thence through conductor I5I to one terminal of the motor, from theother terminal of the motor through conductor 91, th right hand contactsof switch 93, and thence through conductor 94 back to the other side ofthe main current supply.

The motor now being energized starts to operate the blower and pumpingmechanisms. The action of cylinder 32 draws heated oil through themetering valve, and the carburetor I68 where air is combined with theoil as previously described, it being understood that the valve 98 is soregulated that when the switches 99 and 93 are actuated as justdescribed, the valve 98 will also be opened to admit air to thecarburetor.

At the same time, cylinder 3| starts drawing in air which is compressedand combined with the attenuated mixture discharged from cylinder 32.The mixed oil and air is then conducted through pipe I 25 to the nozzleI6, where oil is atomized into a combustion supporting atmosphereproduced by the air issuing from the blower A through the extension I 5.

Simultaneously with the starting of the motor, energization of the motorcompletes a circuit through the primary of an ignition transformer asfollows: from one side'of the main current supply I4I, through thecontacts of the safety switch, conductor I42, contacts I 3!, conductor I5I, conductor I 53, contacts I31, conductor I54 to one terminal of theprimary of the ignition transformer, from the other primary terminalthrough conductor I35, and thence through conductor I44 back to theother side of the supply circuit. The ignition transformer thus beingenergized, an ignition spark is emitted adjacent the nozzle I6 between apair of electrodes I56 which are respectively connected by conductorsI51 and I58 to the respective ends of the secondary winding of theignition transformer.

Assuming now that the atomized fuel'issuing from the nozzle I6 isignited, the hot gases passing out the flue of the furnace will actuatethe flue thermostat to such position that it will open its contacts I 31and disconnect the ignition transformer. At the same time it will closeits contacts I38 which operate to short circuit the heater I35 of thesafety switch through the following circuit: from one terminal of theheater, through conductor I46, conductor I59, contacts I38, conductorI69, and thence through conductor I41 to the other terminal of theheater coil I35.

The burner will now continue to operate until suflicient heat isfurnished to the room containing the room thermostat. When-thetemperature has reached the amount for which the room thermostat is set,it will open its contacts I49 and thereupon opeh-cirouit the secondarycoil I29 of the repulsion relay. The secondary coil then moves towardsthe primary coil and opens the contacts I3I, whereupon the motorcircuitis deenergizedand the burner discontinues its operation'. j

In the event that the ignition spark doesnot ignite the atomized fuelissuing from the nozzle It, then the: flue thermostat continues toretain contacts I31 closed. Since the contacts of switch 90 are at thistime opened, the heating coil I35 will be in the room thermostat circuitof the sec.- ondary coil I251; The heating coil I35 is thus energizedfrom the secondary coil I29, and due to its heating effect upon thethermostatic strip of himetal l34, this latch will be deflected after apredetermined interval of time to a position where.- in it will releasethe safety switch 132, so that the mercury switch I35 will be movedunder the action of its biasing spring. to a position wherein it willopen its contacts and shut down" the motor driving the burner. Theburner will then be left out until such time as the safety switch ismanually reset.

When the burner shuts down, the air which has become stored in the tankIll will open the bleeder valve H6 and be discharged through the pipeI25 and nozzle l5, thus purging and cleaning out the system.

If, for any reason during the operation of the oil burner, the nozzle 16should become clogged so as to prevent the atomization of the attenuatedfluid thereby, a pressure will build up behind the nozzle. In myimproved system, this pressure is relieved by the opening of reliefvalve H4 which permits the passage of fluid from the outlet manifold ofthe reciprocating pump mechanism through the by-pass valve HZ back tothe supply tank.

If the burner has been operating continuously or atsufiiciently closeintervals to have kept the oil in the casing 2| of the reciprocatingpumping mechanism at a sufliciently high temperature, the burner willstart upimmediately upon a call for heat by the room thermostat andthere will not be instituted the time delay previously described forenergizing the heater 59 for preheating the oil.

From the foregoing description, it will be apparent that the presentinvention provides an improved oil burner and system which willefficiently and economically burn the heavier and more viscous oil;.whichincludes improved means for preheating the oil; which is soarranged that air may be mixedwith the oil under pressure toform acombustible mixture, before the mixture is atomized in. the burnernozzle, the amount of air being automatically controlled; which embodiesimproved means for carbureting the, oil

by theinjection of air before the oil reaches theburner nozzle; whichincludes novel pumping mechanism in which the oil may be pro-heated andmixed with air under pressure; which is provided with improved means forpurging and flushing the oil nozzle, when the burner is shut down;

which has an improved relief arrangement in the oil path, whereby oilmay be returned to a source of supply whenever the burner nozzle becomesclogged; a burner arranged to utilize metered quantitiesof oil andby-pass surplus pumped oil back to a supply source; and which utilizes;improved control means for delaying starting of the burner, when cold,until the oil has been preheated to a predetermined temperature.

Now, it is, of course, to be understood that although I have describedin detail the preferred embodiment of my invention, the invention is notto-be thus limitedvbut only insofar as defined by the scope and spiritof the appended claims.

A I claim as myinvention:

In an oil burner construction in which mixed airand oil are supplied to"a. fuel nozzle,v an air aeezsaa.

supply, an oil supply, pumping means for pump ing air and oil from saidsupplies and delivering mixed air and. oil to said nozzle, means forpreheating the oil, and means responsive to the temperature of thepreheated oil for controlling the amount of air supplied to the pumpingmeans.

2:. In an oil burner construction of the type in which mixedair and oilare supplied to a fuel nozzle for injection into an entraining,combustion supporting atmosphere, an air supply, an oil supply, pumpingmeans for pumping air and oil from said supplies and delivering mixedair and oil to said nozzle, means for heating the oil, and control meansresponsive to the temperature of said heated oil for starting theentrainment of said mixed air and oil into-said combustion supportingatmosphere; said control means including a valve in said air supply.

3. An oil burner comprising a fuel atomizing nozzle, an oil pump, meansfor heating the pumped oil, a carburetor for mixing air with the heatedoil to form an attenuated mixture, pumping means for compressing theattenuated mixture, and means for adding additional compressed air tothe attenuated mixture and delivering it to said nozzle where it isatomized, and means for delivering a main air supply to the atomizedmixture.

4. Oil burning apparatus comprising a nozzle,

pumping means comprising, a pump device for pumping oi-l only at onestage, another pump device for supplying air under pressure at anotherstage, and an additional pumping device for pumping combined air and oilat a third stage, means for conducting the combined air and oilto saidnozzle, and means for pro-heating. the oil prior to its being combinedwith said air.

5. Oil burning apparatus comprising a fuel nozzle, a pumpmechanismhaving separate elements for respectively pumping oil, air, andoombinedoil and, air, means for heating the oil before it is combined with theair, means for conducting the combined oil and air to said nozzle,- andmeans for supplying combustion supporting air to said nozzle.

6. In an oil burner in which oil and air are combined to form acombustible mixture; a fuel delivery nozzle, pumping means for supplyingthe combustible mixture: to said, nozzle, means for pre-heating the oil,temperature responsive means for energizin the oil pro-heating means, athermally actuated mechanism responsive to the temperature of the"pro-heated oil for simultaneously starting the burner and de-energizing'the pre-heating means, and means surrounding and in heat receivingrelation to said nozzle for continuing the heating of said oil duringnormal burner operation.

7. In oil burning apparatus, a nozzle, a casing defining a reservoir foroil, pumping elements in. said reservoir casing, certain of saidelements being arranged to pump air and others of the elements beingarranged to pump oil. from said reservoir, and means for pre-heating theoil and pumping-- elements insaid; casing, a; manifold connecting theoutlets of said pumping elementsfor mixing oiland air therein,. andmeans con-' meeting said nozzle; with said manifold;

8. In an oil burner, a pump having. separate chambers, a combination oiland air inlet arrangernentto one or said chambers, air inlet means to;the Second of said chambers, each of; said chambers having an outlet,. amanifold enclosing; said outlets within which additional air. from theSecond. chamber'is mixed with: the oil and air mixture from the firstchamber, a valve governing the admission of air into said combinationinlet arrangement, and means associated with said valve governing theair passing therethrough in accordance with the temperature of the pump.

9. In an oil burner in which liquid fuel and air are combined to form acombustible mixture, a liquid fuel supply, a first pumping means forpumping fuel from said supply, means for preheating said pumped fuel, ahousing forming a reservoir to receive said pre-heated fuel, heatingmeans arranged to further heat the preheated fuel in said reservoir, asecond pumping means to remove heated fuel from said reservoir, acarburetor for mixing air with the heated fuel from said reservoir toform an attenuated mixture which is received and compressed by saidsecond pumping means, thermal means responsive to the temperature offuel in said reservoir to control the operation of said second pumpingmeans, additional means in said second pumping means to add additionalcompressed air to the attenuated mixture to form a combustible mixture,a fuel atomizing nozzle for receiving said combustible mixture, andmeans to deliver a main air supply to the combustible mixture atomizedby said nozzle.

10. In an oil burner having a blower provided with electricallyenergized driving means and in which oil and air are combined to form acom- 10 bustible mixture, a fuel delivery nozzle, pumping means fordelivering the combustible mixture to said nozzle, electricallyenergized means to preheat the oil handled by said pumping means,temperature responsive means for energizing the 15 oil pre-heatingmeans, a thermally actuated mechanism responsive to the temperature ofthe pre-heated oil and including bellows means, electric supplycircuits, and switches actuated by said bellows means for opening andclosing said 20 circuits for simultaneously starting the blower andde-energizing the pre-heating means.

CHARLES L. RAYFIELD.

